Statistical Calculator

Margin of Error for a Proportion

Formula

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Large (Infinite) Populations

e = zs/sqrt(n)

where:

z = 
2.576 for 99% level of confidence
1.96 for 95% level of confidence
1.645 for 90% level of confidence

s = sqrt(p(1-p))    p = proportion

n  = sample size

 

Finite Populations

e = zs/sqrt(n_adj)

where:

z = 
2.576 for 99% level of confidence
1.96 for 95% level of confidence
1.645 for 90% level of confidence

s = sqrt(p(1-p))    p = proportion

n_adj = (N-1)n/(N-n)    n = sample size  N = population size